我国20 m预应力T梁桥承载能力可靠度分析

为了准确掌握我国20 m预应力T梁桥承载能力可靠度,基于我国公路钢筋混凝土及预应力混凝土桥涵设计规范(JTG 3362—2018),利用大型结构有限元分析软件Midas-civil建立了公路-Ⅰ级设计荷载作用下20 m预应力T梁全桥三维有限元模型,分析了最不利工况下桥梁的内力,并基于承载能力极限状态可靠度方法,计算了该类桥梁的承载能力可靠度,与美国和欧洲的可靠度计算值进行了比较。结果表明:我国20 m预应力T梁桥恒载最大弯矩为1516.7 kN·m,活载产生的最大弯矩为1386.4 kN·m,我国的活载效应值和美国基本一致,欧洲的活载效应较大;活荷载效应值对桥梁结构可靠度计算结果影响较大,我国20 m预应力T梁桥可靠度指标β为5.478,大于我国规范值约17%,高于美国的4.43,但低于欧洲的7.25。

Reliability Analysis of Bearing Capacity of 20 m Prestressed T-beam Bridge in China

In order to accurately grasp the reliability of bearing capacity of 20 m prestressed T-beam bridge in China,based on the code for design of highway reinforced concrete and prestressed concrete bridges and culverts(JTG 3362—2018),a three-dimensional finite element model of 20 m prestressed T-beam bridge under class I design load is established by using Midas civil,a large-scale structural finite element analysis software,to calculate the interior of the bridge under the most unfavorable conditions.Based on the ultimate state reliability method of bearing capacity,the bearing capacity reliability of this kind of bridge is analyzed and compared with that of the United States and Europe.The results show that the most unfavorable moment of 20 m prestressed T-beam bridge caused by dead load is 1516.7 kN·m,and the most unfavorable moment caused by live load is 1386.4 kN·m;the value of live load effect in China is basically the same as that in the United States,and that in Europe is the largest;The effect value of live load has great influence on the calculation result of bridge structural reliability.The reliabilityβof 20 m prestressed T-beam bridge in China is 5.478,which is about 17%higher than the standard value in China,higher than 4.43 that in the United States,but lower than 7.25 that in Europe.